Mixed feelings for this Irish team pre-date Martin O'Neill, yet they've seldom been more palpable than under the lights of a conflicted Lansdowne last night.

They've become an enigma, almost wilfully unknowable. Capable of thrilling competitive aggression when the mood takes them, yet inclined to turn up every once in a while with all the fury of dead house-plants. How to reconcile the two faces? Of, say, Tbilisi on Saturday and Vienna before it? Of a largely indecipherable formation to crystalline focus?

Serbia were too strong here, Aleksandar Kolarov's 55th minute thunderbolt perhaps inflicting terminal damage on Irish hopes of making it to the World Cup in Russia.

We could have foretold that Ireland would rediscover their aggression. They played with energy and edge, looking tuned in, adversarial. But there was little enough to rekindle memories of Euro 2016, to reawaken the sense of a team vivid with life and the ambition to push through defensive lines. To go after a supposedly more polished team, trusting themselves as distinct from just rolling dice.

How do you figure out the pathology of this condition? This gift for great courage and small beauties one day, for looking frazzled and remote the next?

The simplistic view proposes Wes Hoolahan as the key and, last night, Hoolahan played at the tip of a midfield diamond, oiling Ireland's creative play with a subtlety not accessible through any other player.

Strolling

It took the ex-Belvedere boy just ten minutes to unlock the Serbian rearguard, a sublime right-wing delivery finding Shane Duffy who, sadly, was waved offside as he headed powerfully past Vladimir Stojkovic.

Yet twice in those early minutes Serbia worked clear openings, the Irish defence ripped apart with disconcerting ease. Nemanja Matic, especially, was asserting almost nonchalant authority in the engine-room, strolling about with an air of grandeur.

Ireland met such refinement with unbridled aggression, yet that too had its complications, worry rising exponentially every time James McClean made contact with a red shirt. Just seven minutes had elapsed when the Turkish referee felt compelled to warn Ireland's number 11 for a needlessly intemperate challenge on Antonio Rukavina.

And that was the early tenor of it, Ireland working furiously to assert their will and, maybe on some level, looking to give the game the temperature of a gang-fight.

Trouble was, the Serbs looked comfortable with those terms of engagement. They are a big team, un-fussed at high intensity. They should have scored in the 33rd minute, Aleksandar Mitrovic failing to get sufficiently clean contact in the Irish box to beat Darren Randolph. Soon after, Rukavina spooned wildly over.

To be fair to O'Neill, the best performances at last year's Euros found expression with a midfield in which James McCarthy and Jeff Hendrick became influential figures. Maybe even more importantly, they found expression with Seamus Coleman evolving into a hugely formidable captain.

O'Neill is currently denied all three of these men and it's a handicap being starkly felt.

For the Serbs were formidable opponents here, all the individual parts coalescing sweetly, albeit the ageing legs of men like Branislav Ivanovic and Kolarov did look potential targets. The latter appeared pedestrian when turned, but that textbook finish was an essay in quality. And quality would be the difference.

On the line, O'Neill had the disposition of an increasingly agitated traffic policeman, gesticulating wildly as the rhythms of the evening turned against him.

He altered the team's shape and philosophy just over the hour mark, replacing Hoolahan with Daryl Murphy. What did that substitution say? The re-adjustment to 4-4-2 seemed to arrive as a tacit admission that he could see no further promise in guile or subtlety. It was time to deploy the battering-ram.That decision drew an unhappy soundtrack from the stands but it was momentarily forgotten six minutes later when a rash challenge from the last defender, Nikola Maksimovic, on a charging Murphy drew red from the Turkish referee.

With an extra man, the onus was now on Ireland to make the pitch bigger, a challenge for which Hoolahan might, presumably, have been useful. O'Neill responded by sending in Callum O'Dowda and it was while trying to get to O'Dowda's left-wing across that Murphy seemed to be blatantly held by Jagos Vukovic in the area, yet no penalty.

Watching you were entitled to ask what exactly does O'Neill want Ireland to be? Where is the tactical clarity?

Murphy did, it is true, carry a physical threat and he was nearest to an Irish goal in the 86th minute, but his snap shot was straight at Stojkovic. Ireland were now pretty desperate and one-dimensional, just spooning long deliveries into the opposition box in the hope of a lucky break. It was flailing football, lacking lucidity of movement and clarity of thought.

Soon news came drifting through of a breakthrough goal for Wales in Moldova, the realisation hardening that Russia, suddenly, looked an eternity away now after four pretty ruinous days. McClean finally got an almost inevitable booking in the 74th minute, ruling him out of the next game against Moldova, a fixture Robbie Brady misses too.

The roar greeting an announcement of five added minutes pretty much captured the broad sense of rising desperation. Yet Serbia knew the breadth of what was coming from Ireland. It wasn't complicated. And for a team of big men it wasn't especially challenging.

So Ireland's campaign looked to be going up on cinder blocks here, O'Neill rushing away with a head full of worries. The sarcasm he deploys under awkward questioning sometimes communicates precisely what he is trying to avoid. In trying to feign calmness under pressure, he can seem surly and mean-spirited...

Trying to hum Dixie, yet only emitting a growl.

Today, he must answer the sharpest queries about structure and shape and, maybe above all, about football philosophy.